With the development of communications network technologies, signal processing has become one important branch of the communications network technologies. In a communication process, during transmission of a signal, the signal is inevitably interfered with by an interference signal sent by another signal source, leading to poor quality of a signal received by a receive end, where a higher density of the another signal source indicates stronger interference to the signal, poorer quality of the signal received by the receive end, and poorer communication quality. For example, a signal received by an antenna on a pole is a mixed signal that is interfered with, where the mixed signal includes a desired signal needing to be received and an interference signal sent by another antenna. When there are a relatively large quantity of antennas on the pole, intense adjacent-channel interference is generated; in this case, the interference signal included in the received mixed signal has excessively large energy strength, and the receive end cannot recognize the desired signal from the mixed signal. In order to reduce adjacent-channel interference, so that the receive end can recognize the desired signal from the mixed signal, in an existing processing method, a global power adjustment solution is used. That is, power used by some antennas to send desired signals is reduced, so as to reduce interference to receiving of the desired signals by other antennas. In this way, the interference signal included in the mixed signal received by the receive end has relatively small energy strength, so that the receive end can recognize the desired signal from the mixed signal. In the processing method, although adjacent-channel interference can be reduced, so that the receive end can recognize the desired signal from the mixed signal, receiving quality of the desired signal is affected; therefore, the method is not practical.